A stoppage time header by fullback Lucas Vazquez earned 10-man Real Madrid a 1-0 victory at lowly Alaves.
Levante claim that Barcelona's teenage defender Chumi Brandariz, who played in the first leg, was ineligible to take part in the match because he was suspended.
Sevilla midfielder Aleix Vidal will join treble winners Barcelona.
Busquets, who retired from international duty last year, has made more than 700 appearances for Barcelona and holds the record for playing in more El Clasicos than any other player with 48 appearances against Barcelona's rivals Real Madrid.
Bayern Munich coach Pep Guardiola is now backing his former club Barcelona.
Rafael Nadal survived a difficult start to see off Chung Hyeon of South Korea in straight sets and reach the semi-finals of the Barcelona Open for a 10th time on Friday.
A statement from the club on Thursday said they had made record turnover of 990 million euros last season and projected an increase to 1.047 billion euros for the 2019/20 campaign.
Champions Real Madrid were beaten at home by promoted Cadiz, while Barcelona fell to their first defeat in La Liga under new coach Ronald Koeman as they lost to Getafe.
Lionel Messi scored twice as Barcelona crushed Getafe 5-2 on Thursday to stay in the hunt for the La Liga title.
Barcelona has decided to leave Neymar out of the decisive El Clasico against Real Madrid because of the legal uncertainty over an appeal to overturn his suspension
'Trust me, the comeback of Leo Messi only depends on him.'
Neymar will play in the Olympics in August and will miss the Centenary Copa America in the United States in June, his club Barcelona said on Wednesday to end months of speculation.
La Liga champions Barcelona fell to their first defeat in three games under new coach Quique Setien as they were beaten 2-0 away at Valencia on Saturday. Barca are still top of the standings on 43 points after 21 games but second-placed Real Madrid, who are also on 43, can go three points clear at the summit if they beat Real Valladolid away from home on Sunday.
Juventus climb to top of Serie A with win over Lecce
Barcelona twice threw away the lead to draw 3-3 at Levante on Tuesday in a potentially fatal blow to their chances of winning the La Liga title.
'The PSG performance gives us hope and belief we can do it, but we are playing against the favourites'
La Liga club Barcelona have expressed their support for Argentine striker Lionel Messi and his father after the Spanish Supreme Court upheld their prison sentences over tax fraud charges, although neither are expected to go to jail.
Portugal's Cristiano Ronaldo, who has won the award five times, did not receive a nomination for the first time in 20 years.
'We want not only to defend it but also show that we are superior and we need to have a good game'
Real Madrid midfielder Luka Modric came off the bench to net a stunning strike from the edge of the box late in the second half to secure a 1-0 home win over Sevilla on Sunday and stretch their lead at the top of La Liga to eight points.
Barcelona are keen to sign the Brazilian playmaker, who joined Liverpool from Inter Milan for 8.5 million pounds ($11.03 million) in 2013, and have already had an initial bid worth 80 million euros rejected by Liverpool last month.
While Sunday's clash was the last time Klopp and Guardiola will face off for Premier League points, as far as this year's title race is concerned it merely made things even more interesting with Arsenal ahead of Liverpool on goal difference and City one point back. All three have 10 games left.
Canadian pop sensation Justin Bieber had a fan boy moment when he visited the FC Barcelona training base on Monday.
Barcelona coach Ernesto Valverde will be banking on new signing Ousmane Dembele to fill the gap left by Neymar's departure as he looks to overcome off-pitch difficulties when the Catalans take on Espanyol on Saturday.
Brazilian forward Neymar has been cleared of fraud but still faces a corruption trial in Spain in connection with the value of his 2013 transfer from Santos to Barcelona, the Spanish National High Court said on Thursday.
Lionel Messi lifted Barcelona out of their recent slump with two goals in a vintage display as his side survived a tenacious Tottenham Hotspur fightback to claim a 4-2 victory in Champions League Group B on Wednesday.
Manchester City boss Pep Guardiola said he will miss his old sparring partner Juergen Klopp when the Liverpool manager calls time on his reign at the end of the season.
Barcelona were so keen to bring Neymar back from Paris St Germain that the players were ready to accept delays to salary payments in order for the club to afford the Brazilian
Calling his side 'weak', 'inconsistent' and 'very easy to score against', Lionel Messi called for urgent changes
Sergio Busquets called on Barcelona to sign more players after the club's 3-1 Spanish Super Cup defeat by Real Madrid on Sunday.
Unstoppable duo Andres Iniesta and Lionel Messi helped Barcelona thrash Sevilla 5-0 to win the King's Cup final for the fourth consecutive season on Saturday as they close in on a likely domestic double.
Barcelona have launched a campaign in support of Lionel Messi and his father Jorge after the Argentine pair were sentenced to prison terms this week over tax fraud.
Sporting director Leonardo Araujo, back for a second stint in the role, has said the Brazilian can leave if a buyer is found.
Summary of all that transpired on and off the football field
Barcelona's last Champions League triumph came in 2015, and since then they have failed to get beyond the quarter-finals while Real Madrid have monopolised the trophy.
The 25th Laureus World Sports Awards will take place in Madrid, Spain on April 22, it was announced on Wednesday.
Lionel Messi's double strike helped Barcelona scrape a 3-2 victory over Real Sociedad on Saturday to keep the pressure on La Liga leaders Real Madrid, who needed a brace from Isco to beat Sporting Gijon by the same scoreline.
Brazilian striker Neymar Jr is leaving FC Barcelona, the Catalan club confirmed on Wednesday, as a radio report said he was moving to French team Paris Saint-Germain.
Barca are unbeaten and nine points clear at the top of La Liga this season.
Barcelona have joined captain Andres Iniesta in calling for dialogue between the Spanish government and leaders in Catalonia to resolve the crisis between the central government and its richest region following Sunday's disputed referendum.